1. Field of the Invention
The present invention relates to the manufacture of contact lenses, and more particularly, to a method and apparatus for molding, automatically inspecting and packaging contact lenses, and to a contact lens mold used in such a method and apparatus.
2. Description of the Related Art
Conventionally, a soft contact lens is molded using a two-sided mold in which one side of the mold includes a convex surface and the other side of the mold includes an opposing concave surface, and in which a cavity for forming the lens is defined by the opposing convex and concave surfaces. A lens is formed by placing a lens material on one of the convex and concave surfaces, bringing the two sides of the mold together to form the lens cavity and separating the two sides of the mold to expose the cast lens after polymerization of the lens material.
Furthermore, techniques are generally known for controlling the adhesion of the molded lens upon separation of the two sides of the mold, i.e., for causing the molded lens to exhibit an affinity to adhere to one of the convex and concave surfaces upon separation of the two sides of the mold. The utilization of such techniques helps eliminate the time consuming, manual labor that is otherwise required in determining which surface the transparent molded lens has adhered to after separation of the two sides of the mold. For example, European Patent Application Publication No. 0367513 discloses a technique for ensuring that the molded lens remains in contact with one side of the mold by flame polishing the convex surface of the one side of the mold. Furthermore, U.S. Pat. No. 4,197,266 discloses that by fabricating the two sides of the mold with materials which, while both wettable, have different degrees of wettability, one can insure that the molded lens will adhere to the desired surface of the mold upon separation. Additionally, U.S. Pat. No. 4,150,073 discloses that the adhesion of the molded lens may be controlled by exposing a mold surface to monomeric vapors.
However, conventional techniques for making contact lenses suffer various drawbacks.
For example, in manufacturing the contact lens, lens material of a sufficient quantity to exceed the volume of the cavity is placed on one of the mold surfaces, and then the two sides to the mold are brought together to form the lens cavity. The quantity of excess lens material is collected within the mold body, along the outer periphery of the lens cavity, to form a ring of excess polymerized lens material. Conventionally, upon separation of the lens mold, this ring of excess lens material is located by visual inspection and then removed manually.
Furthermore, after the lens has been molded and the mold separated, testing of certain physical characteristics of the molded lens must be carried out. Conventionally, each individual molded lens is manually removed from the mold, and placed on a test tray. Light is then transmitted through the lens and directed into a screen where certain deformities in the lens may be visually detected. Still further, additional manual handling of each lens is necessary to place the lens in a lens package containing, for example, saline solution.
In general, the manufacture of contact lenses is conventionally labor intensive, requiring manual handling and visual inspection of the cast lens during several stages of production, and further requiring manual removal of the ring of excess lens material.